Field of the Invention
The technique disclosed herein relates to paper sheet stacking mechanisms and paper sheet handling devices.
Description of the Background Art
Japanese Laid-Open Patent Publication No. 2015-26118 (hereinafter referred to as Patent Literature 1) discloses a paper sheet handling device including a paper sheet stacking mechanism configured to stack, therein, paper sheets such as banknotes, checks, negotiable instruments, and the like. The paper sheet stacking mechanism is provided with: a pair of stacking wheels; two rollers provided on the sides of the respective stacking wheels so as to be coaxial with the stacking wheels; and transport belts provided to be opposed to the rollers. Each stacking wheel has a base, and a plurality of vanes extending outward from an outer circumferential surface of the base in a direction opposite to a rotation direction of the stacking wheel. Paper sheets are inserted between the vanes of the stacking wheels, and the stacking wheels transport the paper sheets one by one to a stacking unit. The two rollers rotate at an angular velocity greater than that of the stacking wheels. The transport belts and the rollers nip the paper sheets, and the paper sheets are transported by a driving force of the transport belts to be inserted between the vanes of the stacking wheels. In this paper sheet stacking mechanism, each paper sheet is assuredly inserted between the vanes of the stacking wheels, and the inserted paper sheet is prevented from being pushed out from between the vanes due to an elastic restoring force of the paper sheet. This paper sheet stacking mechanism can stably stack the paper sheets in the stacking unit.
The paper sheet stacking mechanism disclosed in Patent Literature 1 further includes a first auxiliary roller and second auxiliary rollers. The first auxiliary roller has a diameter larger than the diameter of the base of each stacking wheel, and is provided between the pair of stacking wheels so as to be rotatable. A leading end portion of a paper sheet inserted between the vanes of the stacking wheels by the transport belts and the rollers comes into contact with an outer circumferential surface of the first auxiliary roller. The first auxiliary roller prevents the paper sheet from being excessively inserted between the vanes of the stacking wheels.
The second auxiliary rollers each have a diameter smaller than the diameter of the two rollers, and are provided on the sides of the two rollers, respectively. The second auxiliary rollers prevent both end portions of a paper sheet from being folded while the stacking wheels are rotating or from being caught in a gap in the stacking unit.
The paper sheet stacking mechanism disclosed in Patent Literature 1 is effective in terms of stably stacking the paper sheets in the stacking unit, particularly in a structure having miniaturized stacking wheels.
Meanwhile, the inventor of the present disclosure has found through an investigation that, if the rotation speed of the stacking wheels is increased in the paper sheet stacking mechanism disclosed in Patent Literature 1 having the miniaturized stacking wheels, paper sheets may be folded or the leading ends of paper sheets may be damaged.
The technique disclosed herein is made in view of the aforementioned problem, and an object of the technique is to prevent paper sheets from being folded or damaged when the paper sheets are stacked.
According to the investigation of the inventor of the present disclosure, it is found that, if the rotation speed of the stacking wheels is increased in the paper sheet stacking mechanism disclosed in Patent Literature 1, a paper sheet to be forcibly inserted between the vanes of the stacking wheels by the driving force of the transport belts is excessively inserted between the vanes, which causes the paper sheet to be folded or damaged.
That is, in the paper sheet stacking mechanism disclosed in Patent Literature 1, the roller is disposed on one side of each stacking wheel, and the first auxiliary roller is disposed on the other side of the stacking wheel. The roller and the auxiliary roller each have a diameter larger than the diameter of the base of the stacking wheel.
On the other hand, a gap between a vane and a neighbouring vane in each stacking wheel is provided so as to extend outward in a direction opposite to the rotation direction of the stacking wheel from the outer circumferential surface of the base of the stacking wheel. Therefore, the greater the amount of insertion of a paper sheet between the vanes of the stacking wheel is, the more the paper sheet is shifted radially inward in the stacking wheel.
The paper sheet inserted between the vanes of the stacking wheels is nipped between the vanes and the outer circumferential surfaces of the rollers and between the vanes and the outer circumferential surface of the first auxiliary roller. That is, the outer circumferential surfaces of the rollers and the outer circumferential surface of the first auxiliary roller come into contact with a face, of the paper sheet, facing radially inward, and the vanes come into contact with a face, of the paper sheet, facing radially outward. Thereby, the paper sheet is bent in a wave-like shape between the stacking wheels, the rollers, and the first auxiliary roller, and is held between the vanes of the stacking wheels against an elastic restoring force of the paper sheet. Even when the stacking wheels are miniaturized and the rotation speed thereof is increased, it is possible to stably hold the paper sheet between the vanes of the stacking wheels if the paper sheet is, inserted to a moderate extent between the vanes.
However, as described above, the greater the amount of insertion of the paper sheet inserted between the vanes of the stacking wheels is, the more the paper sheet is shifted radially inward in the stacking wheels. Therefore, if the paper sheet is excessively inserted between the vanes, the position at which the outer circumferential surfaces of the rollers and the outer circumferential surface of the first auxiliary roller come into contact with the face, of the paper sheet, facing radially inward, greatly deviates in the radial direction from the position at which the vanes come into contact with the face, of the paper sheet, facing radially outward. That is, the paper sheet, which is shaped in a wave-like shape by being nipped between the vanes and the outer circumferential surfaces of the rollers and between the vanes and the outer circumferential surface of the first auxiliary roller, is greatly bent so as to increase the amplitude of the wave, which causes the paper sheet to be folded.
Furthermore, the greater the amount of insertion of the paper sheet inserted between the vanes of the stacking wheels is, the more the holding force for holding the paper sheet between the vanes is increased, whereby the paper sheet can be stably held between the vanes of the stacking wheels as described above.
With rotation of the stacking wheels, the leading end of the paper sheet held between the vanes hits a stopper, so that the paper sheet comes off from the vanes and is stacked in the stacking unit. With increase in the rotation speed of the stacking wheels, an impact force generated when the leading end of the paper sheet hits the stopper is increased. In addition, as the amount of insertion of the paper sheet is greater and the holding force is greater, the paper sheet cannot easily come off from the vanes when the leading end thereof hits the stopper. Thus, the leading end of the paper sheet is damaged.
Therefore, the inventor of the present disclosure prevents a paper sheet from being folded and/or damaged, by preventing excessive insertion of the paper sheet between the vanes of the stacking wheel.